Lost neutral, or something else?

[GeoffTitch]

OK, I think I may now understand. The two cores going to the pumproom are simply 'passing through' that mini-CU, from the supply to the CU in the pumproom - is that correct?

Correct. Well, not yet it's not, but that was my proposal.

If so (a) those cores would need switch-fuse protection

Yes, I can see that now, because effectively they are 25 metres leads from the mains to the CU...

...and (b) given the size of SWA you are thinking about, there's no way that you are going to be able to do that wiring within a standard 'mini-CU, if that's what we are talking about - at the least, you would need a decent sized one.

Yes. Well I was thinking of 10mm SWA, but as the mains is being carried 25 metres down two of the cores, I am now thinking that 25mm is required.

However, in view of the need for a switch-fuse, an alternative arrangement would probably be used

Funny, from the conversation I was just thinking that I need to rethink it!

e.g. terminating the SWA in another box and taking feeds to that from (a) the mini-CU and (b) from the Henleys, via switch-fuse (for the supply to the poolroom CU).

Yes, I can see that. But am I right in thinking that because two of the cores (feeding the CU 25 metres away in the poolroom) are carrying full mains all the way to the switch fuse that 10mm is not sufficient?

If, as in the normal domestic installation, the distance from the supply (meter) is less than 2-3 metres, then additional protection of that cabling is not deemed necessary. However, if the distance from supply to CU is longer than that, fuse protection is considered necessary.

Thanks John, makes perfect sense.

 

[JohnW2]

If so (a) those cores would need switch-fuse protection

Yes, I can see that now, because effectively they are 25 metres leads from the mains to the CU...

Indeed - and protected by nothing other than the supplier's service fuse, if you don't have the switch-fuse.

Yes. Well I was thinking of 10mm SWA, but as the mains is being carried 25 metres down two of the cores, I am now thinking that 25mm is required. .............. But am I right in thinking that because two of the cores (feeding the CU 25 metres away in the poolroom) are carrying full mains all the way to the switch fuse that 10mm is not sufficient?

That is something that your electrician will have to determine, based on the length of the cable (which we know) and the (present and possibly future) loads to be served by the cable.

However, in view of the need for a switch-fuse, an alternative arrangement would probably be used - e.g. terminating the SWA in another box and taking feeds to that from (a) the mini-CU and (b) from the Henleys, via switch-fuse (for the supply to the poolroom CU).

Yes, I can see that.

I would suspect that your electrician may well favour something like that.

Kind Regards, John

 

[GeoffTitch]

John,

Thank you for taking the time to answer my questions - I feel much more confident talking to my electrician about what I need, and what he is suggesting.

 

[JohnW2]

John, Thank you for taking the time to answer my questions - I feel much more confident talking to my electrician about what I need, and what he is suggesting.

You're welcome. It would be interesting if you could let us know,in due course, what your electrician decides/recommends.

Kind Regards, John